1. Field of the Invention
The invention pertains generally to the field of missiles. In greater particularity of invention pertains to missile guidance and tracking sensor systems. In still greater particularity, the invention pertains to the sensor platforms for the above systems. In yet greater particularity, the invention pertains to gimbal sensor platforms. By way of further characterization, the invention relates to the bail bearings of gimbal supported sensors of missile sensor platforms.
2. Description of the Prior Art
A purpose of a missile sensor platform is to allow the missile sensor to have limited independent movement within the confines of the missile body. This independent movement allows the sensor to focus upon a target and relay information to the missile guidance system as to the relative position of the target with respect to the missile. By mounting the sensor within orthogonally arranged inner and outer bails, isolation of the sensor from the relative movement of the missile can be obtained. The achievement of accurate sensor information using this method is highly dependent upon the precise alignment and movement of the bails relative to their missile base. Complicating this goal are the severe vibrations and loadings the sensor system must endure not only while under operation, but also while being ferried by its delivering platform. Further, weight and size limitations demand proper respect.
Numerous designs for maintaining precision bail alignment and movement have been developed. They have all, however, enjoyed only a limited success. Current methods of aligning the outer bail involve the use of bearing races made a part of the outer edges of the bail itself. A common scheme is to allow the outer bail to ride upon rollers. The rollers mate with a soft metal bearing race cut into the bail's edges. Because of weight and dimensional constraints, a few rollers of relatively large size are utilized. The effect of this design is a concentration of vibrational and other loadings over a small segment of the bail. Another tried method has been to cut a recirculating bearing path into the platform base, thereby allowing circulating ball bearings to contact hardened steel bearing races inserted into the outer edge of the bail. A current example of this design has balls circulating about an axis perpendicular to the outer bails's axis of rotation. Dimensional limitations require the balls to negotiate tight corners, the result of which lessens the smoothness of the bail movement.